I asked my hoster and he could not found this IP as blocked. He also found no filter that could be involved.Unless the IP adress called adresses who are in/administrator/ folder. Could this be possible?

The thing is that we are not able to access your website from our server and the reason most likely is that you are blocking us, since we are able to access your site from a different server from the same network.

You will see our IP address instead of the visitor's/bots IP because all the requests for the translated pages go through our server. I can see the same error. If you whitelisted our our IP address it should work properly. Can you check your website first request load time? It should be less than 5 sec.

You need to talk about this with your hosting provider, if they are not able to solve it, you may use cloudflare, so we will grab your original content from cloudflare servers, or you may consider changing your hosting.

I have also tried from a different server from the same network and different IP address and it worked, so I think that it is related to IP address only.